The role of galectin-3 in atrial fibrillation

Numerous risk factors for atrial fibrillation (AF) progression have been identified. However, the biomarkers mentioned in the guidelines do not have any clinically relevant predictive value. Some research groups investigated the potential utility of galectin-3 (gal-3) as a diagnostic, prognostic, and predictive biomarker in AF. In this review, we have thoroughly summarized the current data on the role of gal-3 in AF based on the original research in this field. Patients suffering from AF present with increased levels of gal-3. The concentration of gal-3 differs between patients with AF depending on the type of AF - it is higher in patients with persistent AF than in patients with paroxysmal AF. Multiple studies investigating the reappearance of AF in patients who underwent ablation have shown that gal-3 is a promising biomarker to predict the outcome of this therapy. Patients with increased levels of gal-3 are at higher risk of AF recurrence. Although the research considered in this work addressed many aspects of the role of gal-3 in AF, most of it has been conducted on a small group of patients. Therefore, further research and extensive clinical trials confirming described findings are highly warranted.

Insights into the Role of Galectin-3 as a Diagnostic and Prognostic Biomarker of Atrial Fibrillation

Atrial fibrillation (AF) is an irregular atrial activity and the most prevalent type of arrhythmia. Although AF is easily diagnosed with an electrocardiogram, there is a keen interest in identifying an easy-to-dose biomarker that can predict the prognosis of AF and its recurrence. Galectin-3 (Gal-3) is a beta-galactoside binding protein from the lectin family with pro-fibrotic and -inflammatory effects and a pivotal role in a variety of biological processes, cell proliferation, and differentiation; therefore, it is implicated in the pathogenesis of many cardiovascular (e.g., heart failure (HF)) and noncardiovascular diseases. However, its specificity and sensitivity as a potential marker in AF patients remain debated and controversial. This article comprehensively reviewed the evidence regarding the interplay between Gal-3 and patients with AF. Clinical implications of measuring Gal-3 in AF patients for diagnosis and prognosis are mentioned. Moreover, the role of Gal-3 as a potential biomarker for the management of AF recurrence is investigated. The association of Gal-3 and AF in special populations (coronary artery disease, HF, metabolic syndrome, chronic kidney disease, and diabetes mellitus) has been explored in this review. Overall, although further studies are needed to enlighten the role of Gal-3 in the diagnosis and treatment of AF, our study demonstrated the high potential of this molecule to be used and focused on by researchers and clinicians.

Interleukin-11 Is Elevated in Patients with Atrial Fibrillation, Correlates with Serum Fibrosis Markers, and Represents a Therapeutic Target for Atrial Fibrosis

INTRODUCTION

Inflammatory cytokines are closely associated with developing cardiac fibrosis. This research aimed to explore the significant role of IL-11 in atrial fibrosis progression and potential therapeutic targets.

METHODS

207 AF patients and 160 healthy subjects were included in the case-control study. Blood samples were analyzed for the level of IL-11 by enzyme-linked immunosorbent assay (ELISA). Angiotensin II (Ang II)-treated fibrosis mouse models were generated, and expression of IL-11 mRNA and protein was detected by RT-qPCR and Western blot. IL-11 antagonist was used to evaluating atrial fibrosis-related markers.

RESULTS

The persistent atrial fibrillation patients (n = 76) had significantly larger left atrial size, higher serum levels of hypertrophic protein BNP, proinflammatory cytokine high-sensitivity C-reactive protein (hs-CRP), and interleukin-6 (IL-6) compared to paroxysmal atrial fibrillation patients (n = 131), and healthy subjects (all p < 0.05). Pearson correlation analysis revealed significant positive correlation between serum IL-11 and cardiac fibrosis markers BNP (r = 0.394, p < 0.001), CTX-I (r = 0.418, p < 0.001), PICP (r = 0.306, p < 0.001), PIIINP (r = 0.335, p < 0.001), and TGF-β1 (r = 0.273, p < 0.001). In the fibrosis mouse model, Ang II infusion significantly upregulated IL-11 mRNA and protein expression in the left atrium of mice (p < 0.05), as well as staining intensity of Masson trichrome, the intensity of α-SMA, and it increased mRNA expression of collagen I and III in atrial tissue. IL-11 antagonist treatment significantly attenuated Masson trichrome, number of α-SMA-positive myofibroblasts in atrial tissue. Also, it significantly reduced the p-ERK1/2 in atrial tissue of mice infused with Ang II (p < 0.05).

CONCLUSIONS

IL-11 is upregulated in the serum of AF patients, and IL-11 inhibitor significantly inhibited Ang II-induced atrial fibrosis, a key pathological feature of AF. Therefore, IL-11 could be a potential therapeutic target for AF.

Predictors of Total Mortality and Serious Arrhythmic Events in Non-Ischemic Heart Failure Patients: The Role of Galectin-3

Fundamento:

A estratificação de risco continua sendo clinicamente desafiadora em pacientes com insuficiência cardíaca (IC) de etiologia não isquêmica. A galectina-3 é um marcador sérico de fibrose que pode ajudar no prognóstico.

Objetivo:

Determinar o papel da galectina-3 como preditora de eventos arrítmicos graves e mortalidade total.

Métodos:

Este é um estudo de coorte prospectivo que incluiu 148 pacientes com IC não isquêmica. Todos os pacientes foram submetidos a uma avaliação clínica e laboratorial abrangente para coleta de dados de referência, incluindo níveis de galectina-3 sérica. O desfecho primário foi a ocorrência de síncope arrítmica, intervenções apropriadas do cardioversor desfibrilador implantável, taquicardia ventricular sustentada ou morte súbita cardíaca. O desfecho secundário foi a morte por todas as causas. Para todos os testes estatísticos, considerou-se significativo o valor p<0,05 (bicaudal).

Resultados:

Em seguimento mediano de 941 dias, os desfechos primário e secundário ocorreram em 26 (17,5%) e 30 (20%) pacientes, respectivamente. A galectina-3 sérica>22,5 ng/mL (quartil mais alto) não foi preditora de eventos arrítmicos graves (HR: 1,98; p=0,152). Os preditores independentes do desfecho primário foram diâmetro diastólico final do ventrículo esquerdo (DDFVE)>73 mm (HR: 3,70; p=0,001), ventilação periódica durante o exercício (VPE) no teste de esforço cardiopulmonar (HR: 2,67; p=0,01) e taquicardia ventricular não sustentada (TVNS)>8 batimentos na monitorização por Holter (HR: 3,47; p=0,027). Os preditores de morte por todas as causas foram: galectina-3>22,5 ng/mL (HR: 3,69; p=0,001), DDFVE>73 mm (HR: 3,35; p=0,003), VPE (HR: 3,06; p=0,006) e TVNS>8 batimentos (HR: 3,95; p=0,007). A ausência de todos os preditores de risco foi associada a um valor preditivo negativo de 91,1% para o desfecho primário e 96,6% para a mortalidade total.

Conclusões:

Em pacientes com IC não isquêmica, níveis elevados de galectina-3 não foram preditores de eventos arrítmicos graves, mas foram associados à mortalidade total. A ausência de preditores de risco revelou um subgrupo prevalente de pacientes com IC com excelente prognóstico.

Potential Biomarkers in Atrial Fibrillation: Insight into their Clinical Significance

ABSTRACT

In risk-stratifying patients with atrial fibrillation (AF), physicians rely heavily on clinical parameters that provide risk scores and determine treatment strategies. There has been increasing research on potential biomarkers in the blood that could more accurately determine both risk of complications in AF and risk of incidence of AF. This review highlights the clinical significance of five novel biomarkers that have been shown to be linked to AF. These biomarkers are carbohydrate antigen 125 (CA-125), galectin-3 (gal-3), growth differentiating factor-15 (GDF-15), a member of the interleukin 1 receptor family, IL1RL1 (ST2) and N-terminal pro B-type natriuretic peptide (NT-proBNP).

Preoperative Levels of the Soluble Urokinase-Type Plasminogen Activator Receptor as Predictor for New Episodes of Atrial Fibrillation After Vascular Surgery

INTRODUCTION

The soluble urokinase-type plasminogen activator receptor (suPAR) in uPAR soluble form is produced when the uPAR is cleaved from the cell membrane during the inflammatory process. Postoperative atrial fibrillation (AF) is the most common perioperative cardiac arrhythmia. It is speculated that elevated suPAR has a role in the development of AF. The aim of our study was to investigate the predictive role of preoperative suPAR in the occurrence of AF during the first 6 months after major vascular surgery.

METHODS

We included 119 male and 63 female patients with an average age of 67.19 ± 6.02 years, without permanent/persistent AF. Basic predictive model (BASIC) included traditional risk factors for AF: age, gender, body mass index-BMI, smoking status, presence of arterial hypertension, diabetes mellitus and dyslipidemia.

RESULTS

Over the 6-month period, 19 (10.4%) patients had one new episode of atrial fibrillation and 2 patients (1.1%) had 2 episodes of paroxysmal atrial fibrillation. Paroxysms of AF were significantly more frequent in patients who had a resection of an abdominal aneurysm than in patients with other types of major vascular surgery. BASIC had good discriminatory ability in the prediction of AF paroxysms during the first 6 months after surgery (AUC = 0.715, 95%CI 0.590-0.840). Adding suPAR to the basic model significantly improved the discriminative ability of the predictive model for AF episodes (ΔAUC = 0.238, p < 0.001). The predictive performance of the model BASIC+CRP+suPAR, measured using AUC, NRI and IDI statistics, was very similar to the model BASIC+suPAR.

CONCLUSION

AF is a common complication in surgical patients with high mortality and morbidity. suPAR could improve the ability of traditional risk factors to predict its occurrence up to 6 months after major vascular surgery.

Galectin-3 Induces Atrial Fibrosis by Activating the TGF-β1/Smad Pathway in Patients with Atrial Fibrillation

BACKGROUND

Atrial fibrosis plays a critical role in the occurrence and maintenance of atrial fibrillation. The role of TGF-β1 in mediating atrial fibrosis is well documented. The β-galactoside-binding lectin galectin-3 (Gal-3) is mainly produced by macrophages in biological events such as inflammation and angiogenesis. Previous studies have shown that Gal-3 is associated with atrial fibrosis, but the relationship between TGF-β1 and Gal-3 in atrial fibrosis remains unclear.

OBJECTIVE

To determine whether Gal-3 induces atrial fibrosis and atrial fibrillation by activating the TGF-β1/Smad pathway and whether the expression of Gal-3 is mediated by TGF-β1, which can enable assessing the relationship between Gal-3 and TGF-β1 in atrial fibrosis.

METHODS

In this study, 30 patients' right atrial appendages were collected and divided into 3 groups: congenital heart disease sinus rhythm group (n = 10, as a control group), rheumatic heart disease sinus rhythm group (n = 10), and rheumatic heart disease atrial fibrillation group (n = 10). Rat atrial fibroblasts were cultured in vitro, and recombinant Gal-3 and recombinant TGF-β1 proteins were added to the cell culture. The expression of Gal-3, TGF-β1, Smad2, and collagen I was detected by Western blotting and quantitative real-time PCR. Atrial tissues were stained with Masson's trichrome stain to evaluate the extent of atrial fibrosis. The expression of Gal-3 and TGF-β1 was detected by immunohistochemical staining and immunofluorescence staining. Gal-3 and TGF-β1 interaction was demonstrated by immunoprecipitation.

RESULTS

The expression levels of Gal-3, TGF-β1, Smad2, and collagen I were elevated in the rheumatic heart disease atrial fibrillation group compared with the congenital heart disease sinus rhythm group and the rheumatic heart disease sinus rhythm group. In cultured atrial fibroblasts, there is a synergistic interaction between Gal-3 and TGF-β1. Gal-3 stimulated the TGF-β1/Smad pathway, and overexpression of TGF-β1 induced Gal-3 expression.

CONCLUSIONS

Gal-3 and TGF-β1 interact with each other and stimulate the downstream TGF-β1/Smad pathway. This finding suggests that Gal-3 could be an important factor in TGF-β1-induced fibrosis in atrial fibrillation.

Galectin-3 and risk of atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Galectin-3 is an inflammatory marker that is raised in myocardial fibrosis and inflammation. Recent studies have explored its role in predicting atrial fibrillation (AF) outcomes. The aim of this systematic review and meta-analysis is to examine the association between serum concentration of galectin-3 and AF.

METHODS

PubMed, EMBASE, and the Cochrane Database were searched. A total of 280 studies were identified, of which 28 studies involving 10 830 patients were included in our meta-analysis.

RESULTS

Galectin-3 is present at higher concentrations in patients with AF than those in sinus rhythm (mean difference [MD] = -0.68 ng/mL, 95% CI: -0.92, -0.44, Z = 5.61, P < .00001). Galectin-3 levels were significantly higher in the persistent AF than in the paroxysmal AF group (MD = -0.94 ng/mL, 95% CI: -1.85, -0.03, Z = 2.04, P = .04). Higher galectin-3 levels were associated with a 45% increase in the odds of developing AF (odds ratio [OR] = 1.45, 95% CI: 1.15, 1.83, Z = 3.11, P = .002) and risk of AF recurrence (hazard ratio [HR] =1.17, 95% CI: 1.06, 1.29, Z = 3.12, P = .002).

CONCLUSIONS

Our meta-analysis found that galectin-3 is significantly higher in patients with persistent AF than in those with paroxysmal AF, and can predict both AF development and recurrence after treatment.

Galectin-3 in Acute Myocardial Infarction Patients with Atrial Fibrillation

OBJECTIVE

Atrial fibrillation (AF) is common in acute myocardial infarction (AMI), and galectin-3 is possibly involved in its occurrence. Galectin-3 has been shown to play a central role in fibrosis and tissue remodeling and has a role in inflammatory and proliferative responses. The aim of our study was to measure galectin-3 levels in patients with myocardial infarction and to compare its levels in patients with or without AF, in order to investigate the potential predictive role of galectin-3 in this setting.

SUBJECTS AND METHODS

The study included 51 consecutive AMI patients with AF; 27 AMI patients (52.9%) had permanent/persistent AF, and 24 patients (47.1%) had paroxysmal AF. Thirty-eight consecutive AMI patients without AF were used as a control group. Blood samples were obtained from venous blood on the third day after reperfusion.

RESULTS

Patients with AF had higher levels of C-reactive protein (p < 0.01) and galectin-3 (p < 0.05) than those without AF. Patients with high galectin-3 had 4.4 times greater odds of having AF. Galectin-3 levels were lower in patients without AF (p < 0.01) than in those with permanent/persistent AF.

CONCLUSION

AMI patients with AF had higher levels of galectin-3 than those without this arrhythmia. This biomarker of inflammation and fibrosis could be a potential target for treating AMI patients at high risk.

Increased serum lysyl oxidase-like 2 levels correlate with the degree of left atrial fibrosis in patients with atrial fibrillation

Atrial fibrillation (AF) progression is generally accompanied by increased atrial fibrosis and atrial structural remodeling. Lysyl oxidase-like 2 (LOXL2) is known to play an important role in many fibrotic conditions, including cardiac fibrosis. The present study aimed to explore the relationship between serum LOXL2 levels and AF. Fifty-four AF patients and 32 control subjects were enrolled in the study. High-density three-dimensional electroanatomic mapping was performed, and mean bipolar voltage was assessed in AF patients. LOXL2 levels were measured by enzyme-linked immunosorbent assay. All patients underwent echocardiography to assess left atrium size and left ventricle function. Serum LOXL2 levels were significantly elevated in AF patients compared with the control group (526.81 ± 316.82 vs 240.94 ± 92.51 pg/ml, P<0.01). In addition, serum LOXL2 level was significantly correlated with the size of the left atrium (LAD) (r² = 0.38, P<0.01). Furthermore, the serum LOXL2 levels were significantly higher in AF patients with LAD ≥ 40 mm compared with those with LAD < 40 mm (664.34 ± 346.50 vs 354.90 ± 156.23 pg/ml, P<0.01). And the Spearman's correlation analysis further revealed that the mean bipolar left atrial voltage was inversely correlated with the LOXL2 (r² = -0.49, P<0.01) in AF patients. Multivariate regression analysis further demonstrated that serum LOXL2 [odds ratio (OR) 1.013, 95% confidence interval (CI) 1.002-1.024, P<0.05] and LAD (OR 1.704, 95% CI 1.131-2.568, P<0.01) were independent predictors of AF. In conclusion, serum LOXL2 levels were significantly elevated and were correlated with the degree of left atrial fibrosis in AF patients.